I can't address the 124 specifically, but I remember seeing charts in a book a few years ago which described BTU capacity of automotive A/C systems using various sizes of York compressors. The figures ranged from 15,000-30,000 BTU if I remember right. The "ton" rating for A/C is equivalent to 12,000 BTU, so your typical car A/C is the equvalent of a pretty good sized central home A/C unit. Remember that cooling a car interior is much harder than a similar sized space in a home because of engine heat, varying compressor shaft speed, and most of all the vast expanse of glass that can't be covered with curtains, venetian blinds, etc.

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Erich Loepke
2010 Ford Focus
Currently Benz-less